Everyone should _______________ the environment.

The rise in wood fuel(燃料) use has __________ the disappearance of forest and the loss of habitats for pandas..

Doctors are doing research to find out what happens physically when people ______ smoking.

 Many people ________ the accident, so it was not difficult to investigate（调查）.

I wonder if your brother will go to the party. If he does, so ______mine.